Autonomously driven, self-propelled mobile platforms are used in various sectors, for example, as industrial trucks in industrial manufacturing or storage, or as transport robots in hospitals, nursing homes, or the like (automated guided vehicle—AGV). When operating self-propelled mobile platforms, various safety aspects must be considered. The safety concept of autonomously driven platforms should be designed in such a way that these vehicles are not able to collide with obstacles and other driven platforms, or if at all, only at low speed. In this context, a speed of the mobile platform below 0.3 m/s is considered to be non-critical. Furthermore, the safety concept must ensure that collisions with people are safely avoided. In this context as well, a speed below 0.3 m/s is considered to be non-critical.
A suitable sensor system is used for a safe operation of the mobile platforms, so that obstacles may be detected in a timely manner and the mobile platform is able to respond appropriately. For example, distance sensors are used which are able to detect frontal obstacles based on wave transit time measurements. It is thus possible to plan and adapt the travel route of the mobile platform accordingly and to drive around obstacles, including people. The higher the travel speed of the mobile platform, the earlier an imminent collision must be detected in order to be able to brake and/or reroute the vehicle appropriately.
Self-propelled mobile platforms are normally equipped with a personal protection sensor system, in which people who are situated in the travel route may be detected with the aid of sensors working in particular in a contact-free manner. Based on such safety sensors, a safety zone may be defined. As soon as a person is detectable in this safety zone, this may be signaled to the drive of the mobile platform via an interface, so that the mobile platform is able to stop or travel more slowly.
The limitation of the field of vision of the aforementioned safety sensors when entering an intersection area is especially problematic for safe operation. The corridor walls impede the “vision” of the distance sensors toward possibly approaching obstacles (people) which to move within a corridor opening into the intersection. Therefore, the maximum speed is often reduced before entering an intersection area, and is again increased after passing through the intersection. In order for the mobile platform to be able to detect the intersection area at all, either an external indication of the intersection must be present via corresponding markings, for example, via RFID (radio frequency identification) markings or visual marking, or the detection of the intersection must be implemented within the mobile platform via internal measures, for example, via a continuous localization of the mobile platform with respect to data relating to the surroundings. Both solutions are relatively complex, since additional infrastructure measures are required which, being safety-related measures, must also be checked and monitored.
The German patent application DE 11 2011 104 645 T5 describes a mobile robot which may be used as a driverless transport vehicle, this robot being equipped with a dead-zone sensor and in particular with a rotating imaging sensor. With the aid of this sensor, imaging signals may be recorded along the direction of travel in order to be able to detect the location of an object in the surroundings of the robot and maneuver the robot appropriately. The U.S. patent application US 2009/0292393 A1 describes a cleaning robot. In order to be able to perform cleaning in the wall area, the cleaning robot has a wall-following mode, a wall being detected using an appropriate sensor system and the robot being guided along the wall. The European patent application EP 2 120 122 A1 also describes a mobile cleaning robot which is equipped with proximity sensors for detecting obstacles. As soon as an obstacle is thereby detected, the speed of the robot may be reduced in response.